archive-tar.c

   1 /*
   2  * Copyright (c) 2005, 2006 Rene Scharfe
   3  */
   4 #include "cache.h"
   5 #include "tar.h"
   6 #include "archive.h"
   7 #include "streaming.h"
   8 #include "run-command.h"
   9
  10 #define RECORDSIZE      (512)
  11 #define BLOCKSIZE       (RECORDSIZE * 20)
  12
  13 static char block[BLOCKSIZE];
  14 static unsigned long offset;
  15
  16 static int tar_umask = 002;
  17
  18 static int write_tar_filter_archive(const struct archiver *ar,
  19                                     struct archiver_args *args);
  20
  21 /*
  22  * This is the max value that a ustar size header can specify, as it is fixed
  23  * at 11 octal digits. POSIX specifies that we switch to extended headers at
  24  * this size.
  25  *
  26  * Likewise for the mtime (which happens to use a buffer of the same size).
  27  */
  28 #if ULONG_MAX == 0xFFFFFFFF
  29 #define USTAR_MAX_SIZE ULONG_MAX
  30 #else
  31 #define USTAR_MAX_SIZE 077777777777UL
  32 #endif
  33 #if TIME_MAX == 0xFFFFFFFF
  34 #define USTAR_MAX_MTIME TIME_MAX
  35 #else
  36 #define USTAR_MAX_MTIME 077777777777ULL
  37 #endif
  38
  39 /* writes out the whole block, but only if it is full */
  40 static void write_if_needed(void)
  41 {
  42         if (offset == BLOCKSIZE) {
  43                 write_or_die(1, block, BLOCKSIZE);
  44                 offset = 0;
  45         }
  46 }
  47
  48 /*
  49  * queues up writes, so that all our write(2) calls write exactly one
  50  * full block; pads writes to RECORDSIZE
  51  */
  52 static void do_write_blocked(const void *data, unsigned long size)
  53 {
  54         const char *buf = data;
  55
  56         if (offset) {
  57                 unsigned long chunk = BLOCKSIZE - offset;
  58                 if (size < chunk)
  59                         chunk = size;
  60                 memcpy(block + offset, buf, chunk);
  61                 size -= chunk;
  62                 offset += chunk;
  63                 buf += chunk;
  64                 write_if_needed();
  65         }
  66         while (size >= BLOCKSIZE) {
  67                 write_or_die(1, buf, BLOCKSIZE);
  68                 size -= BLOCKSIZE;
  69                 buf += BLOCKSIZE;
  70         }
  71         if (size) {
  72                 memcpy(block + offset, buf, size);
  73                 offset += size;
  74         }
  75 }
  76
  77 static void finish_record(void)
  78 {
  79         unsigned long tail;
  80         tail = offset % RECORDSIZE;
  81         if (tail)  {
  82                 memset(block + offset, 0, RECORDSIZE - tail);
  83                 offset += RECORDSIZE - tail;
  84         }
  85         write_if_needed();
  86 }
  87
  88 static void write_blocked(const void *data, unsigned long size)
  89 {
  90         do_write_blocked(data, size);
  91         finish_record();
  92 }
  93
  94 /*
  95  * The end of tar archives is marked by 2*512 nul bytes and after that
  96  * follows the rest of the block (if any).
  97  */
  98 static void write_trailer(void)
  99 {
 100         int tail = BLOCKSIZE - offset;
 101         memset(block + offset, 0, tail);
 102         write_or_die(1, block, BLOCKSIZE);
 103         if (tail < 2 * RECORDSIZE) {
 104                 memset(block, 0, offset);
 105                 write_or_die(1, block, BLOCKSIZE);
 106         }
 107 }
 108
 109 /*
 110  * queues up writes, so that all our write(2) calls write exactly one
 111  * full block; pads writes to RECORDSIZE
 112  */
 113 static int stream_blocked(const unsigned char *sha1)
 114 {
 115         struct git_istream *st;
 116         enum object_type type;
 117         unsigned long sz;
 118         char buf[BLOCKSIZE];
 119         ssize_t readlen;
 120
 121         st = open_istream(sha1, &type, &sz, NULL);
 122         if (!st)
 123                 return error("cannot stream blob %s", sha1_to_hex(sha1));
 124         for (;;) {
 125                 readlen = read_istream(st, buf, sizeof(buf));
 126                 if (readlen <= 0)
 127                         break;
 128                 do_write_blocked(buf, readlen);
 129         }
 130         close_istream(st);
 131         if (!readlen)
 132                 finish_record();
 133         return readlen;
 134 }
 135
 136 /*
 137  * pax extended header records have the format "%u %s=%s\n".  %u contains
 138  * the size of the whole string (including the %u), the first %s is the
 139  * keyword, the second one is the value.  This function constructs such a
 140  * string and appends it to a struct strbuf.
 141  */
 142 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
 143                                      const char *value, unsigned int valuelen)
 144 {
 145         int len, tmp;
 146
 147         /* "%u %s=%s\n" */
 148         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
 149         for (tmp = len; tmp > 9; tmp /= 10)
 150                 len++;
 151
 152         strbuf_grow(sb, len);
 153         strbuf_addf(sb, "%u %s=", len, keyword);
 154         strbuf_add(sb, value, valuelen);
 155         strbuf_addch(sb, '\n');
 156 }
 157
 158 /*
 159  * Like strbuf_append_ext_header, but for numeric values.
 160  */
 161 static void strbuf_append_ext_header_uint(struct strbuf *sb,
 162                                           const char *keyword,
 163                                           uintmax_t value)
 164 {
 165         char buf[40]; /* big enough for 2^128 in decimal, plus NUL */
 166         int len;
 167
 168         len = xsnprintf(buf, sizeof(buf), "%"PRIuMAX, value);
 169         strbuf_append_ext_header(sb, keyword, buf, len);
 170 }
 171
 172 static unsigned int ustar_header_chksum(const struct ustar_header *header)
 173 {
 174         const unsigned char *p = (const unsigned char *)header;
 175         unsigned int chksum = 0;
 176         while (p < (const unsigned char *)header->chksum)
 177                 chksum += *p++;
 178         chksum += sizeof(header->chksum) * ' ';
 179         p += sizeof(header->chksum);
 180         while (p < (const unsigned char *)header + sizeof(struct ustar_header))
 181                 chksum += *p++;
 182         return chksum;
 183 }
 184
 185 static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
 186 {
 187         size_t i = pathlen;
 188         if (i > 1 && path[i - 1] == '/')
 189                 i--;
 190         if (i > maxlen)
 191                 i = maxlen;
 192         do {
 193                 i--;
 194         } while (i > 0 && path[i] != '/');
 195         return i;
 196 }
 197
 198 static void prepare_header(struct archiver_args *args,
 199                            struct ustar_header *header,
 200                            unsigned int mode, unsigned long size)
 201 {
 202         xsnprintf(header->mode, sizeof(header->mode), "%07o", mode & 07777);
 203         xsnprintf(header->size, sizeof(header->size), "%011lo", S_ISREG(mode) ? size : 0);
 204         xsnprintf(header->mtime, sizeof(header->mtime), "%011lo", (unsigned long) args->time);
 205
 206         xsnprintf(header->uid, sizeof(header->uid), "%07o", 0);
 207         xsnprintf(header->gid, sizeof(header->gid), "%07o", 0);
 208         strlcpy(header->uname, "root", sizeof(header->uname));
 209         strlcpy(header->gname, "root", sizeof(header->gname));
 210         xsnprintf(header->devmajor, sizeof(header->devmajor), "%07o", 0);
 211         xsnprintf(header->devminor, sizeof(header->devminor), "%07o", 0);
 212
 213         memcpy(header->magic, "ustar", 6);
 214         memcpy(header->version, "00", 2);
 215
 216         xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header));
 217 }
 218
 219 static void write_extended_header(struct archiver_args *args,
 220                                   const unsigned char *sha1,
 221                                   const void *buffer, unsigned long size)
 222 {
 223         struct ustar_header header;
 224         unsigned int mode;
 225         memset(&header, 0, sizeof(header));
 226         *header.typeflag = TYPEFLAG_EXT_HEADER;
 227         mode = 0100666;
 228         xsnprintf(header.name, sizeof(header.name), "%s.paxheader", sha1_to_hex(sha1));
 229         prepare_header(args, &header, mode, size);
 230         write_blocked(&header, sizeof(header));
 231         write_blocked(buffer, size);
 232 }
 233
 234 static int write_tar_entry(struct archiver_args *args,
 235                            const unsigned char *sha1,
 236                            const char *path, size_t pathlen,
 237                            unsigned int mode)
 238 {
 239         struct ustar_header header;
 240         struct strbuf ext_header = STRBUF_INIT;
 241         unsigned int old_mode = mode;
 242         unsigned long size, size_in_header;
 243         void *buffer;
 244         int err = 0;
 245
 246         memset(&header, 0, sizeof(header));
 247
 248         if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
 249                 *header.typeflag = TYPEFLAG_DIR;
 250                 mode = (mode | 0777) & ~tar_umask;
 251         } else if (S_ISLNK(mode)) {
 252                 *header.typeflag = TYPEFLAG_LNK;
 253                 mode |= 0777;
 254         } else if (S_ISREG(mode)) {
 255                 *header.typeflag = TYPEFLAG_REG;
 256                 mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
 257         } else {
 258                 return error("unsupported file mode: 0%o (SHA1: %s)",
 259                              mode, sha1_to_hex(sha1));
 260         }
 261         if (pathlen > sizeof(header.name)) {
 262                 size_t plen = get_path_prefix(path, pathlen,
 263                                               sizeof(header.prefix));
 264                 size_t rest = pathlen - plen - 1;
 265                 if (plen > 0 && rest <= sizeof(header.name)) {
 266                         memcpy(header.prefix, path, plen);
 267                         memcpy(header.name, path + plen + 1, rest);
 268                 } else {
 269                         xsnprintf(header.name, sizeof(header.name), "%s.data",
 270                                   sha1_to_hex(sha1));
 271                         strbuf_append_ext_header(&ext_header, "path",
 272                                                  path, pathlen);
 273                 }
 274         } else
 275                 memcpy(header.name, path, pathlen);
 276
 277         if (S_ISREG(mode) && !args->convert &&
 278             sha1_object_info(sha1, &size) == OBJ_BLOB &&
 279             size > big_file_threshold)
 280                 buffer = NULL;
 281         else if (S_ISLNK(mode) || S_ISREG(mode)) {
 282                 enum object_type type;
 283                 buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);
 284                 if (!buffer)
 285                         return error("cannot read %s", sha1_to_hex(sha1));
 286         } else {
 287                 buffer = NULL;
 288                 size = 0;
 289         }
 290
 291         if (S_ISLNK(mode)) {
 292                 if (size > sizeof(header.linkname)) {
 293                         xsnprintf(header.linkname, sizeof(header.linkname),
 294                                   "see %s.paxheader", sha1_to_hex(sha1));
 295                         strbuf_append_ext_header(&ext_header, "linkpath",
 296                                                  buffer, size);
 297                 } else
 298                         memcpy(header.linkname, buffer, size);
 299         }
 300
 301         size_in_header = size;
 302         if (S_ISREG(mode) && size > USTAR_MAX_SIZE) {
 303                 size_in_header = 0;
 304                 strbuf_append_ext_header_uint(&ext_header, "size", size);
 305         }
 306
 307         prepare_header(args, &header, mode, size_in_header);
 308
 309         if (ext_header.len > 0) {
 310                 write_extended_header(args, sha1, ext_header.buf,
 311                                       ext_header.len);
 312         }
 313         strbuf_release(&ext_header);
 314         write_blocked(&header, sizeof(header));
 315         if (S_ISREG(mode) && size > 0) {
 316                 if (buffer)
 317                         write_blocked(buffer, size);
 318                 else
 319                         err = stream_blocked(sha1);
 320         }
 321         free(buffer);
 322         return err;
 323 }
 324
 325 static void write_global_extended_header(struct archiver_args *args)
 326 {
 327         const unsigned char *sha1 = args->commit_sha1;
 328         struct strbuf ext_header = STRBUF_INIT;
 329         struct ustar_header header;
 330         unsigned int mode;
 331
 332         if (sha1)
 333                 strbuf_append_ext_header(&ext_header, "comment",
 334                                          sha1_to_hex(sha1), 40);
 335         if (args->time > USTAR_MAX_MTIME) {
 336                 strbuf_append_ext_header_uint(&ext_header, "mtime",
 337                                               args->time);
 338                 args->time = USTAR_MAX_MTIME;
 339         }
 340
 341         if (!ext_header.len)
 342                 return;
 343
 344         memset(&header, 0, sizeof(header));
 345         *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
 346         mode = 0100666;
 347         xsnprintf(header.name, sizeof(header.name), "pax_global_header");
 348         prepare_header(args, &header, mode, ext_header.len);
 349         write_blocked(&header, sizeof(header));
 350         write_blocked(ext_header.buf, ext_header.len);
 351         strbuf_release(&ext_header);
 352 }
 353
 354 static struct archiver **tar_filters;
 355 static int nr_tar_filters;
 356 static int alloc_tar_filters;
 357
 358 static struct archiver *find_tar_filter(const char *name, int len)
 359 {
 360         int i;
 361         for (i = 0; i < nr_tar_filters; i++) {
 362                 struct archiver *ar = tar_filters[i];
 363                 if (!strncmp(ar->name, name, len) && !ar->name[len])
 364                         return ar;
 365         }
 366         return NULL;
 367 }
 368
 369 static int tar_filter_config(const char *var, const char *value, void *data)
 370 {
 371         struct archiver *ar;
 372         const char *name;
 373         const char *type;
 374         int namelen;
 375
 376         if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
 377                 return 0;
 378
 379         ar = find_tar_filter(name, namelen);
 380         if (!ar) {
 381                 ar = xcalloc(1, sizeof(*ar));
 382                 ar->name = xmemdupz(name, namelen);
 383                 ar->write_archive = write_tar_filter_archive;
 384                 ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
 385                 ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
 386                 tar_filters[nr_tar_filters++] = ar;
 387         }
 388
 389         if (!strcmp(type, "command")) {
 390                 if (!value)
 391                         return config_error_nonbool(var);
 392                 free(ar->data);
 393                 ar->data = xstrdup(value);
 394                 return 0;
 395         }
 396         if (!strcmp(type, "remote")) {
 397                 if (git_config_bool(var, value))
 398                         ar->flags |= ARCHIVER_REMOTE;
 399                 else
 400                         ar->flags &= ~ARCHIVER_REMOTE;
 401                 return 0;
 402         }
 403
 404         return 0;
 405 }
 406
 407 static int git_tar_config(const char *var, const char *value, void *cb)
 408 {
 409         if (!strcmp(var, "tar.umask")) {
 410                 if (value && !strcmp(value, "user")) {
 411                         tar_umask = umask(0);
 412                         umask(tar_umask);
 413                 } else {
 414                         tar_umask = git_config_int(var, value);
 415                 }
 416                 return 0;
 417         }
 418
 419         return tar_filter_config(var, value, cb);
 420 }
 421
 422 static int write_tar_archive(const struct archiver *ar,
 423                              struct archiver_args *args)
 424 {
 425         int err = 0;
 426
 427         write_global_extended_header(args);
 428         err = write_archive_entries(args, write_tar_entry);
 429         if (!err)
 430                 write_trailer();
 431         return err;
 432 }
 433
 434 static int write_tar_filter_archive(const struct archiver *ar,
 435                                     struct archiver_args *args)
 436 {
 437         struct strbuf cmd = STRBUF_INIT;
 438         struct child_process filter = CHILD_PROCESS_INIT;
 439         const char *argv[2];
 440         int r;
 441
 442         if (!ar->data)
 443                 die("BUG: tar-filter archiver called with no filter defined");
 444
 445         strbuf_addstr(&cmd, ar->data);
 446         if (args->compression_level >= 0)
 447                 strbuf_addf(&cmd, " -%d", args->compression_level);
 448
 449         argv[0] = cmd.buf;
 450         argv[1] = NULL;
 451         filter.argv = argv;
 452         filter.use_shell = 1;
 453         filter.in = -1;
 454
 455         if (start_command(&filter) < 0)
 456                 die_errno("unable to start '%s' filter", argv[0]);
 457         close(1);
 458         if (dup2(filter.in, 1) < 0)
 459                 die_errno("unable to redirect descriptor");
 460         close(filter.in);
 461
 462         r = write_tar_archive(ar, args);
 463
 464         close(1);
 465         if (finish_command(&filter) != 0)
 466                 die("'%s' filter reported error", argv[0]);
 467
 468         strbuf_release(&cmd);
 469         return r;
 470 }
 471
 472 static struct archiver tar_archiver = {
 473         "tar",
 474         write_tar_archive,
 475         ARCHIVER_REMOTE
 476 };
 477
 478 void init_tar_archiver(void)
 479 {
 480         int i;
 481         register_archiver(&tar_archiver);
 482
 483         tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
 484         tar_filter_config("tar.tgz.remote", "true", NULL);
 485         tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
 486         tar_filter_config("tar.tar.gz.remote", "true", NULL);
 487         git_config(git_tar_config, NULL);
 488         for (i = 0; i < nr_tar_filters; i++) {
 489                 /* omit any filters that never had a command configured */
 490                 if (tar_filters[i]->data)
 491                         register_archiver(tar_filters[i]);
 492         }
 493 }